One example of a method of manufacturing chips from a semiconductor-related member such as a silicon wafer may be mentioned as follows. First, a semiconductor-related-member processing sheet, which comprises a base material and a pressure sensitive adhesive layer, is prepared, and the surface of the sheet at the side of the pressure sensitive adhesive layer is attached to a surface of a semiconductor-related member on which circuits are formed (this surface may be referred to as a “member front surface” in the present description). The semiconductor-related member is then ground from the side of an exposed surface opposite to the member front surface to reduce the thickness of the semiconductor-related member. Subsequently, another semiconductor-related-member processing sheet is attached to the ground surface of the semiconductor-related member (this surface may be referred to as a “member back surface” in the present description), and the semiconductor-related-member processing sheet attached to the member front surface is removed. Thereafter, a dividing process is performed for the semiconductor-related member to which the other semiconductor-related-member processing sheet is attached, and a structure is obtained in a state in which many chips are attached to the surface of the other semiconductor-related-member processing sheet at the side of the pressure sensitive adhesive layer. Finally, the chips can be obtained after being individually picked up from the structure.
Thus, when manufacturing chips from a semiconductor-related member, work to attach a semiconductor-related-member processing sheet to and remove it from the surface of the semiconductor-related member or the surfaces of the chips (including pickup work, here and hereinafter) may sometimes be performed. Semiconductor-related members may have a reduced thickness of about several tens micrometers as in the case of a silicon wafer after grinding, and therefore, enhancing the removability of semiconductor-related-member processing sheets is an important issue in regard to quality control of the semiconductor-related members.
The “removability” as used in the present description refers to one of properties of a semiconductor-related-member processing sheet, i.e. a property of avoiding quality issues, such as cracks and breakage, of an adherend when removing the semiconductor-related-member processing sheet from the adherend (a semiconductor-related member or chips in a state in which the semiconductor-related-member processing sheet is attached thereto may be referred to as an “adherend” in a collective term, here and hereinafter). The suitability for pickup, which is a property of avoiding cracks, breakage, etc. of chips by reducing the force applied to the chips when picking up the chips from a dicing sheet, can be positioned as one specific example of the above removability. By using a semiconductor-related-member processing sheet which is excellent in the removability, the problems such as cracks and breakage of an adherend are unlikely to occur when removing the semiconductor-related-member processing sheet from the adherend.
To enhance the removability of a semiconductor-related-member processing sheet, the pressure sensitive adhesive layer of the sheet is ordinarily designed such that the pressure sensitive adhesive property is reduced by a specific stimulus, which may be irradiation of an energy ray such as ultraviolet ray and electron ray.
In view of eliminating pickup failure, i.e. in view of enhancing the removability in pickup from a dicing tape, Patent Literature 1 discloses a technique of including a free epoxy group-containing compound in a pressure sensitive adhesive layer.